Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
char g[55][55];
int dp[55][55];
int dx[4] =  {0,0,1,-1};
int dy[4] =  {1,-1,0,0};
int n,m;
bool ch(int x,int y){
	return (x>=1 and y>=1 and x<=n and y<=m);
}
int main() {
	cin>>n>>m; 
	int s = 0;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>g[i][j];
			if(g[i][j]=='.')s++;
		}
	}
	queue<pair<int,int> > q;
	q.push({1,1});
	dp[1][1] = 1;
	while(!q.empty()){
		int x = q.front().first;
		int y = q.front().second;
		q.pop();
		for(int i=0;i<4;i++){
			int xx = x+dx[i];
			int yy = y+dy[i];
			if(!ch(xx,yy))continue;
			if(g[xx][yy]=='#')continue;
			if(dp[xx][yy])continue;
			dp[xx][yy] = dp[x][y]+1;
			q.push({xx,yy});
		}
	}
	if(dp[n][m])cout<<s-dp[n][m]<<endl;
	else cout<<-1<<endl;
	return 0;
}